In my opinion, the bias toward using Macs today is based on the long-standing history and tradition of graphic designers using Macs. It’s not a practical one (in my opinion), but it is a reason: t radition. You will, in fact, be judged by whether or not you use or own a Mac as a g raphic designer.
In reality, these “marketing optics” do matter to some people, even if they shouldn’t. Many designers feel that if they can’t afford a Mac, they won’t be taken seriously, so they’ll even invest in buying a used Mac that costs twice as much as a newer PC. Many designers find themselves turned down for jobs if they prefer using a Windows PC rather than a Mac. It’s astounding to me that in 2015, the question of which operating system you should use is still a debate.